The Fortaleza de São Sebastião is a historic fortress located in Ilhabela, Brazil. Built in the 16th century, it was designed to protect the region from pirate attacks and foreign invasions. The fortress features thick stone walls and strategic positioning overlooking the sea, making it a significant military structure of its time. Today, the fortress is a popular tourist attraction, offering visitors a glimpse into Brazil's colonial past. It houses a small museum that showcases artifacts and exhibits related to the history of the fortress and the surrounding area, providing educational insights into the region's heritage.